Such a machine is known from U.S. Pat. No. 6,539,710 B2. The first section comprises an externally toothed gear wheel that interacts with an internally toothed ring. Pressure pockets are formed between the gear wheel and the ring, said pressure pockets being either provided with pressure fluid or connected to a low-pressure area via a rotary valve slide arrangement. The gear wheel is connected to the shaft via a cardan shaft. The gear wheel engages a crank pin that transfers the orbiting movement of the gear wheel to a sensor shaft.
U.S. Pat. No. 4,593,555 describes a hydraulic motor, in which a pressure sensor is used to determine the rotary speed of the shaft.
U.S. Pat. No. 6,062,123 describes an auxiliary force supported steering arrangement with a motor and a sensor that detects a position of a steering handwheel. The sensor is arranged radially to the axis of the steering handwheel.
DE 198 24 926 C2 describes a further hydraulic steering arrangement, in which the front side of an inner control slide is provided with a row of teeth, which can be detected by a sensor.
DE 10 2005 036 483 B4 describes a hydraulic rotary machine whose shaft is provided with a transmitter, which has on its outer circumference a toothed structure of teeth and grooves. In the housing is arranged a transmitter that directs a light beam to the threaded structure. From the threaded structure, the light beam is reflected to a receiver.
In many application areas of such machines, in particular hydraulic rotary machines, sensors are required in order to enable sufficiently accurate control of the machine, for example in connection with a connected diesel motor, with the purpose of saving energy.
The sensor arrangements in the machines as mentioned in the introduction have principally proven their value. However, in many cases they require a relatively complicated installation of the sensor. The sensor will then often be in a position, in which it is actually disturbing. If the sensor is arranged in a position, where it is less disturbing, there is a risk that it cannot directly determine the rotation of the shaft, but is connected to the shaft via several, play-susceptible engagement points. A similar problem occurs, when the shaft can be distorted, for example in connection with large torques within a movement chain.